1. Field of the Invention
The present invention relates to light pens. More particularly, the present invention relates to a light pen where light from a light source is propagated along a light conductive fibre cable to a light receiving and processing station.
2. Description of the Prior Art
It is known to use a pen shaped implement to detect the position of an image on a lighted display such as a Cathode Ray Tube or plasma panel. Typical light pen devices include a light responsive element in the pen tip. When the pen tip is placed to the lighted display, the light responsive element produces a signal that identifies the position of the image selected.
Most improvements in light pens have been directed to the light receiver or light responsive element. For example, various types of photodiodes have been employed as light receptive elements. Additionally, switches have been incorporated into the light pen such that the light responsive element is turned on only when the light pen is pressed to the display. Such an improvement eliminates the possibility of a false reading generated by ambient light impinging on the light responsive element.
More recently, the light responsive element has been located remotely from the light pen to eliminate electrical noise inherent in electrically conductive elements extending from a light pen to a processing station. To this end, an optical link between the light pen and the light responsive element has been incorporated into some light pens as disclosed in U.S. Pat. No. 4,109,146 issued to Hillman.
One disadvantage of such prior art light pens is that they employ a glass or plastic optical element through which light from a lighted display is focused onto the light transmissive medium when the tip of a light pen is pressed to the lighted display. Although such operation allows a light pen user to select a particular lighted display location, it does not allow a light pen user to "browse" through a series or matrix of locations on the lighted display. Thus, there is no way to verify that a correct selection has been made prior to the actual selection. This is a particular disadvantage in the case of electronic gaming equipment where a game player might wish to look at several possible choices before making a final selection. Prior art light pens do not allow the game user this opportunity.
In the gaming environment light pens are subjected to considerable abuse. It is not uncommon for light pens to be placed in ashtrays full of cigarettes or to be left dangling in glasses along with ice cubes and partially consumed drinks. Although the inclusion of a light conductive fibre link between the pen the processing station eliminates the possibility of electrical malfunctions due to such rough treatment, prior art pens of necessity incorporate fragile optical elements. The optical elements or lenses significantly increase production costs of the light pen, make maintenance of a faulty or damaged light pen much more difficult, and are quite delicate and easily broken. In the gaming environment, where light pens are often dashed with the gamesters hope of winning a big jackpot, a glass or plastic lens does not last long.